Milk Thistle Benefits and Side Effects

Health benefits, Uses, Side Effects & More

Milk thistle
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Milk thistle (Silybum marianum) is a plant used in herbal medicine. Said to improve liver function, it's often touted as natural remedy for liver problems, such as hepatitis and cirrhosis.

Available in dietary supplement form, a substance known as silymarin contains a mixture of compounds found in milk thistle (including silybin, silydianin, and silychristin).

Uses for Milk Thistle

While treatment of liver conditions is one of the most common uses for milk thistle, the herb is also said to fight the following health issues:

• gallbladder disorders
high cholesterol
insulin resistance
menstrual problems
Parkinson's disease
seasonal allergies

Some proponents also claim that milk thistle can protect against certain forms of cancer, including breast cancer and prostate cancer.

The Health Benefits of Milk Thistle

Here's a look at the science behind the potential health benefits of milk thistle:

1) Liver Disease

Some preliminary research suggests that silymarin may improve liver function by keeping toxic substances from binding to liver cells. However, studies on the milk thistle's effectiveness in treating liver disorders have yielded mixed results.

For example, most clinical evidence indicates that milk thistle neither improves liver function nor reduces the risk of mortality in people with alcoholic liver disease, hepatitis B, or hepatitis C, according to a report published in the American Journal of Gastroenterology in 2005.

Furthermore, some small studies have shown that milk thistle may improve liver function in people with cirrhosis, while other clinical trials have demonstrated that milk thistle may be of little or no benefit to people with this disease.

2) Diabetes

Several studies have shown that milk thistle may be beneficial for people with diabetes.

The most recent research on milk thistle and diabetes includes a study published in Phytomedicine in 2015. For the study, 40 people with diabetes were treated with either silymarin or a placebo for 45 days. At the study's end, members of the silymarin group showed a greater improvement in antioxidant capacity and a greater reduction in inflammation in comparison to those given the placebo.

According to the study's authors, these findings suggest that silymarin may benefit diabetes patients by reducing oxidative stress (a process known to play a major role in the development of diabetic complications).

Additionally, several small clinical trials conducted in recent years have found that milk thistle may aid in diabetes control by regulating blood sugar levels and preventing the progression of diabetes-related kidney damage.

Learn more about milk thistle and diabetes.

3)  Seasonal Allergies

A small study published in Otolaryngology and Head and Neck Surgery in 2011 shows that silymarin may help treat seasonal allergies.

In a clinical trial involving 94 people with seasonal allergies, researchers observed that those treated with silymarin for one month had a significantly greater improvement in the severity of their symptoms (compared to those given a placebo for one month).

Safety and Side Effects

Milk thistle may trigger a number of side effects, including diarrhea, gas, headache, indigestion, joint pain, and sexual dysfunction. 

Milk thistle may lower your blood sugar levels, so it should be used with caution by people with diabetes and by anyone taking medications or supplements that affect blood sugar levels.

Since there is a theoretical risk that milk thistle could have an estrogen-like effect, people with hormone-sensitive conditions such as endometriosis, uterine fibroids, or cancers of the breast, uterus, or ovaries should avoid milk thistle. Milk thistle may theoretically reduce the effectiveness of oral contraceptives by inhibiting an enzyme called beta-glucuronidase.

In addition, people with allergies to daisies, artichokes, kiwi, common thistle, or plants in the aster family may also be allergic to milk thistle.

Milk thistle supplements haven't been tested for safety and keep in mind that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established. You can get tips on using supplements here, but if you're considering the use of milk thistle supplements, talk with your primary care provider first. 

Where to Find Milk Thistle

Dietary supplements containing milk thistle are sold in many natural-foods stores, drugstores, and stores specializing in herbal products. You can also purchase milk thistle products online.


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Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstances or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.

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